Merlin or Dart heads?????

[396_WAYS_TO_SPIT]

Well.... I have to buy new heads since I cant get a decent set of cores. So i have decied to look tward the cast darts. Does anyone know if these headsflow better than stock? Do I need to run different lenght pushros and valves?
396

[GofastRacer]

Of course they are better than stock but it costs also, I have a nice set of 990's if you want to go on a budget!..

[Jordy]

I've got the Merlins on mine now (as you know) and I was spinning 6K on Saguaro on Sunday. Runs like a champ. Now just have to fine tune it a little. :D

[78Eliminator]

I've got the Merlins on mine now (as you know) and I was spinning 6K on Saguaro on Sunday. Runs like a champ. Now just have to fine tune it a little. :D
I read a post that says you should lock out the timing at 50. I read it on ***boat, so it must be true.....

[Jordy]

I read a post that says you should lock out the timing at 50. I read it on ***boat, so it must be true.....
I thought it was 60. :D

[396_WAYS_TO_SPIT]

How much better do they flow over the 990's? What would be better 320cc's or 345cc's with the merlins? the reason i ask is because the merlins bare are only $489ea through jegs.
Here is my recipe.
454 .30 over
10.7-1 comp (if I run a 119 cc head)
rectangle port tunnel ram with 2 holley 750's dp flowed by braswell
full msd ignition(dist,wires,6al and coil)
cam is a clay smith 256@.50 .615 lift 108lobe
This will be running in a 18ft jet with a "B" impeller. I am trying to spin 5800r's
396

[396_WAYS_TO_SPIT]

I thought it was 60. :D
No,no,no both of you guys are wrong...........
ITS 15 :rollside: :rollside: :rollside: :rollside:
396

[396_WAYS_TO_SPIT]

oh and by the way i am at my 1396th post :D :D
396

[Jordy]

This will be running in a 18ft jet with a "B" impeller. I am trying to spin 5800r's
396
You should be spinning better than 5800 with a b as I'm doing it with an A cut. :D

[396_WAYS_TO_SPIT]

well I have a "A" so its not cut yet. I wont know untill I get that damn heaache in the water :D
396

[Fiat48]

5800 rpm...I would just do the 990's. If you get up around 6800 or up..then the Merlins would be of benefit. That's stock head for stock head of course.
$489 each and then you get to do all the hardware, valve job, etc.
Jordy..It just depends WHAT BOOK OR MAGAZINE ARTICLE the tune up came from. 60 degrees....you may have to lower the % on nitro.

[Jordy]

Jordy..It just depends WHAT BOOK OR MAGAZINE ARTICLE the tune up came from. 60 degrees....you may have to lower the % on nitro.
It was in the ***boat forums, so like Justin said, it just has to be true. :cool:

[396_WAYS_TO_SPIT]

5800 rpm...I would just do the 990's. If you get up around 6800 or up..then the Merlins would be of benefit. That's stock head for stock head of course.
$489 each and then you get to do all the hardware, valve job, etc.
Jordy..It just depends WHAT BOOK OR MAGAZINE ARTICLE the tune up came from. 60 degrees....you may have to lower the % on nitro.
So what your saying is that i wouldnt benefit from a steel merlin head at all :confused: So them all the people that buy aluminum heads an spend 2k on them are wasting money? i am not questioning you at all fiat, i am just trying to understand;) My only concern is that i cant find a decent set of 990's anywhere around here for a decent price.
396

[Fiat48]

So what your saying is that i wouldnt benefit from a steel merlin head at all :confused: So them all the people that buy aluminum heads an spend 2k on them are wasting money? i am not questioning you at all fiat, i am just trying to understand;) My only concern is that i cant find a decent set of 990's anywhere around here for a decent price.
396
I am saying that a motor as small as you run with that compression and 5800 rpm...the head is not so critical in my opinion. The benefit of a merlin STOCK head would be slight at best.
Now if you were more compression, more rpm..more camshaft then yes you would see an improvement.
So if you can't find a set of 990's reasonable..then by all means the cast iron merlin would be the best inexpensive choice.
I'll go further with this. Yes there are a lot of guys who checkbook this performance stuff to death. Let's look at what you have.
460 inches.
10.7 compression ratio. Seems to me that's just about enough to get you in trouble with pump gas. I'm no expert on gas by a long shot. But seems you would be close to needing octane booster. If we go higher on compression..then you will need better gas for sure. So we are stuck here.
Jet boat: Generally speaking jets don't turn high rpm. So why build a high rpm motor? Killer heads that flow at great lifts we are never going to see?
Cam is 256 @ .050 and .615 lift. 108 L/s which I like but the jet guys will tell you wider L/S probably.
So it should be pretty obvious we don't need a "racing" head for what you are going to do, the fuel you are limited to and the boat you have to push.

[396_WAYS_TO_SPIT]

I am saying that a motor as small as you run with that compression and 5800 rpm...the head is not so critical in my opinion. The benefit of a merlin STOCK head would be slight at best.
Now if you were more compression, more rpm..more camshaft then yes you would see an improvement.
So if you can't find a set of 990's reasonable..then by all means the cast iron merlin would be the best inexpensive choice.
Thats why your my go to guy fiat :idea: ;);)

[396_WAYS_TO_SPIT]

I am saying that a motor as small as you run with that compression and 5800 rpm...the head is not so critical in my opinion. The benefit of a merlin STOCK head would be slight at best.
Now if you were more compression, more rpm..more camshaft then yes you would see an improvement.
So if you can't find a set of 990's reasonable..then by all means the cast iron merlin would be the best inexpensive choice.
I'll go further with this. Yes there are a lot of guys who checkbook this performance stuff to death. Let's look at what you have.
460 inches.
10.7 compression ratio. Seems to me that's just about enough to get you in trouble with pump gas. I'm no expert on gas by a long shot. But seems you would be close to needing octane booster. If we go higher on compression..then you will need better gas for sure. So we are stuck here.
Jet boat: Generally speaking jets don't turn high rpm. So why build a high rpm motor? Killer heads that flow at great lifts we are never going to see?
Cam is 256 @ .050 and .615 lift. 108 L/s which I like but the jet guys will tell you wider L/S probably.
So it should be pretty obvious we don't need a "racing" head for what you are going to do, the fuel you are limited to and the boat you have to push.
Well i wanted to be at 12-1 but I would have to run a close chambered head and even if I bought aluminum heads they are all 118cc's. So that drops my compression. I run av gas in my boats so the fuel woulnt be a problem. I will search for a set of 990's or equivelent tomorrow and if no luck then I am making the phone call for a set of steel merlins;) I just want to get this damn thing done. I am loosing alot of sleep over this :frown:
396

[Fiat48]

The word from Chevrolet when the open chamber head was developed (actually was done for emmisions) was the open chamber head gave 50 Hp more than the closed due to improved flame travel in the chamber. I don't remember what rpm that the gain was stated at.
You're number one deal...is to run as much compression....as you can possibly get away with on the gas you run. It's a big deal. Worth the effort.
Did you know a set of 119cc heads can be angle milled and become 110 cc's?
Did you know a set of TRW 12.5 forged pistons can be bought for less than $300?
Find out if you can get away with 13.5 to 1 compression on av gas. Someone will know. I don't.

[396_WAYS_TO_SPIT]

13.5-1 I thnk is out of the limit for av gas but then again I am not sure. I know I wouldnt run avgas on 13.5-1. I heard that you can go up to 12-1 comp then your done on avgas. Someone else might know a better answer than me on this though.
396

[GofastRacer]

It depends on how much lead you run. I ran 12:5 in my 440 on Avgas with Marvel with 36 total, no problems, anything higher I would run race gas!..

[lucky]

do you still have those 990's for sale ???It depends on how much lead you run. I ran 12:5 in my 440 on Avgas with Marvel with 36 total, no problems, anything higher I would run race gas!..
on a side note - since i have booth you guru's on the board - I changed my motor around as art know's ! i'm running a set of the old alum heads that where done by slover porting ( d runners ) its a o ring set up with the wire in the head - I was lapping the valves sunday and really started to inspect the heads i noticed on #1 the water port closest to the head had some electolosist ( spl -) and it was almost to the wire - would like your opinions - i was going to have thgem welded/surfaced and re rung - but i'm almost afraid i'd be opening a new can of worms - I believe these heads must have been in salt at one time ! hell they probably have more stories than you two !!lol then i was talking to my machinest , but did not get to finish our conversation - he wanted me to check to see where felpro's sat in regaurds to the fire ring - i really don't need the cooper gaskets , and was going to try the coated ones to see how well they seal - for my lake cruiser - any advice/experience - just looking for the best option - ( i'm waiting for my machinest to call me back so we can finish our conversation ) tanks -- fiat i'm running around 8;1 compression - 5lbs of boost and a hyd. cam @5.97 lift 114 lobes and i told art it was 247 dur . but i was wrong ( spec book was/is with mota ) duration is around 290 - so it's a pretty mild motor - I have a 671 that i will problably put on it next year - ( 174 holley right now ) thanks

[GofastRacer]

do you still have those 990's for sale ???
on a side note - since i have booth you guru's on the board - I changed my motor around as art know's ! i'm running a set of the old alum heads that where done by slover porting ( d runners ) its a o ring set up with the wire in the head - I was lapping the valves sunday and really started to inspect the heads i noticed on #1 the water port closest to the head had some electolosist ( spl -) and it was almost to the wire - would like your opinions - i was going to have thgem welded/surfaced and re rung - but i'm almost afraid i'd be opening a new can of worms - I believe these heads must have been in salt at one time ! hell they probably have more stories than you two !!lol then i was talking to my machinest , but did not get to finish our conversation - he wanted me to check to see where felpro's sat in regaurds to the fire ring - i really don't need the cooper gaskets , and was going to try the coated ones to see how well they seal - for my lake cruiser - any advice/experience - just looking for the best option - ( i'm waiting for my machinest to call me back so we can finish our conversation ) tanks -- fiat i'm running around 8;1 compression - 5lbs of boost and a hyd. cam @5.97 lift 114 lobes and i told art it was 247 dur . but i was wrong ( spec book was/is with mota ) duration is around 290 - so it's a pretty mild motor - I have a 671 that i will problably put on it next year - ( 174 holley right now ) thanks
Chris, check your e-mail!.. :)

[Dave C]

I switched FROM 990's TO cast Oval port merlins on a jet.
IMO the merlins were just better because they have different port design especially on the exhaust (D shape) and we put a 2.25 valve in it.. They were better at the RPM's the jet was running (i.e. up to 5,500 on mine). I ran an A on a 502, 10.9:1, 254/264 cam.
IMHO at lower RPM's with a smaller cam and CID, the aluminums square ports are a waste of $$.

[LeE ss13]

Art ....
Are your 990 heads legal for SS ?????

[GofastRacer]

Art ....
Are your 990 heads legal for SS ?????
Sorry Larry, they're not legal for SS, they're o-ringed and the chambers have been polished!..

[shaun]

Whats legal for SS mean?

[LeE ss13]

Whats legal for SS mean?
In Super Stock racing, the heads have to be stock with no porting or polishing. Stock valve size. Wadayaasking4them?

[Taylorman]

What is O-Ringed?

[SJ Valley Dave]

We went from the iron 049 oval ports to a set of the Merlin aluminum 305cc runners and have been very happy. We are at 10.5:1 w/ SRP pistons, 2 660's on a tunnel w/ a Comp Cam solid. 260@.050 w/ .629 lift on 108. 18% gears w/ a 11 1/2 x 15 prop and it turns 6700-6900 all day on pump premium. We did go w/ the 2.30 intake & 1.88 exhaust combo. We went aluminum to get a safty margin w/ 10.5:1 on pump

[GofastRacer]

What is O-Ringed?
O-Ring around the chamber just like you would the block!. Actually it's called pantographed since it's not a circle!..

[GofastRacer]

Wadayaasking4them?
I'll take $550 for em!.. :)

[396_WAYS_TO_SPIT]

The word from Chevrolet when the open chamber head was developed (actually was done for emmisions) was the open chamber head gave 50 Hp more than the closed due to improved flame travel in the chamber. I don't remember what rpm that the gain was stated at.
You're number one deal...is to run as much compression....as you can possibly get away with on the gas you run. It's a big deal. Worth the effort.
Did you know a set of 119cc heads can be angle milled and become 110 cc's?
Did you know a set of TRW 12.5 forged pistons can be bought for less than $300?
Find out if you can get away with 13.5 to 1 compression on av gas. Someone will know. I don't.
Ok if you angle mill a set of 118cc heads, would your pushro length change?
Another question, If I was to go with a set of merlins...... They take 11/32 valves. My valves are 3/8, \can i change the guies to accept my 3/8 valves. The reason i ask is because I have a brand new set of severe duty manleys an I dont want to buy another set.
396

[GofastRacer]

Regardless what you do to the heads you don't know if your pushrods are the right lenght until you mock it up and check rocker arm ratio!....Just bore the guides for 3/8 stems!..

[Fiat48]

Ok if you angle mill a set of 118cc heads, would your pushro length change?
Another question, If I was to go with a set of merlins...... They take 11/32 valves. My valves are 3/8, \can i change the guies to accept my 3/8 valves. The reason i ask is because I have a brand new set of severe duty manleys an I dont want to buy another set.
396
Probably will change the pushrod length. And you can have the guides honed out to 3/8". But 11/32 loses a lot of weight in the valve. I would sell the valves you have on Ebay and buy 11/32. Actually I would just by the heads Gofastracer has (provided they were good shape) for $550 and use the money saved on the Merlins to buy the right pistons and wind up with about 12.5 or more compression which will provide power you can feel.
Later down the road if I wanted to move to a more exotic head for whatever reason...there's always somebody looking for a set of 990's.

[Jordy]

Dammit Bob, I keep trying to tell 396 that he needs to be down in the 10:1 range for what he's doing. Running race/av gas gets old really quick on a boat that you want to take to the lake every weekend. The nice thing now about my jet, I just pull up to the pump, top it off with super (which is probably overkill anyway) and roll. No more trips to the aeropuerto with that bad boy. :D
396, I'd rethink that compression deal for what you're looking to do with it.

[78Eliminator]

Dammit Bob, I keep trying to tell 396 that he needs to be down in the 10:1 range for what he's doing. Running race/av gas gets old really quick on a boat that you want to take to the lake every weekend. The nice thing now about my jet, I just pull up to the pump, top it off with super (which is probably overkill anyway) and roll. No more trips to the aeropuerto with that bad boy. :D
396, I'd rethink that compression deal for what you're looking to do with it.
Either way, he doesn't need the merlins..... My old 427 that was .030 over with 990 heads was kicking it with comperable boats that had 125 CIs more than me. Wanna know why? Compression. I would do some fuel research and determine what you can live with. Maybe you can still fill up at the pump with enough bottles of additives on board. But by all means, get as much compression as you possibly can...

[Jordy]

Either way, he doesn't need the merlins..... My old 427 that was .030 over with 990 heads was kicking it with comperable boats that had 125 CIs more than me. Wanna know why? Compression. I would do some fuel research and determine what you can live with. Maybe you can still fill up at the pump with enough bottles of additives on board. But by all means, get as much compression as you possibly can...
396 isn't looking for a race boat, at least that's what he told me. He's looking for something that he can shoot planes out of the sky with the roost. :D :D :D
He's always easy to find on the lake we go to. Just look for the 200' water fountain. :D :D :D

[Fiat48]

Dammit Bob, I keep trying to tell 396 that he needs to be down in the 10:1 range for what he's doing. Running race/av gas gets old really quick on a boat that you want to take to the lake every weekend. The nice thing now about my jet, I just pull up to the pump, top it off with super (which is probably overkill anyway) and roll. No more trips to the aeropuerto with that bad boy. :D
396, I'd rethink that compression deal for what you're looking to do with it.
But he is looking for more power. And trying to come up with compression. And running Av gas anyway. So put as much compression in that thing as your fuel will allow. Compression is power...everywhere. Only bad is the fuel you have to use.
But..there is something to be said for "turn key and pump gas". I understand where you are coming from. Just depends on what he wants to do. Only he knows that.

[Jordy]

But..there is something to be said for "turn key and pump gas".
I've got one of those right now for sure (the pump gas part), and with the new fuel pump I just ordered, I think, hope, and pray that I'll have the other for a while. :D

[78Eliminator]

I've got one of those right now for sure (the pump gas part), and with the new fuel pump I just ordered, I think, hope, and pray that I'll have the other for a while. :D
Bullshit. This winter we throw some huge dome pistons in there......

[Jordy]

Bullshit. This winter we throw some huge dome pistons in there......
Gee, let me think. Um, no? I'm pulling 6K on the tach right now with an "A" impeller. I think I'm happy where I am. Besides they already have domes on them. :)
If anything, like I get the urge to destroy something, I'll just add some giggle gas and go from there. Right now it's been 3 days since I've had a wrench on my boat. I'm going for 4. :D

[78Eliminator]

Right now it's been 3 days since I've had a wrench on my boat. I'm going for 4. :D
That's my point. A couple weeks will go by, and you will want to wrench. We need to get you right at 13:1. :hammer2:

[Jordy]

That's my point. A couple weeks will go by, and you will want to wrench. We need to get you right at 13:1. :hammer2:
I have the Schiada if I want to wrench. I think I'm going to get it running again in the next couple weeks. Should help it move. I'm just enjoying having a running boat right now, although I do need to throw a new battery in it as the optima in there is at least 4 years old and kind of worn out. So there, a new fuel pump and battery and I'll have all the wrenching I need. :D

[lucky]

And Pump Gas -- ???? Its All About Lobe Seperation And Mech Compression Ratio's Cylinder Presure Is The Key To Detonation .

[78Eliminator]

I have the Schiada if I want to wrench. I think I'm going to get it running again in the next couple weeks. Should help it move. I'm just enjoying having a running boat right now, although I do need to throw a new battery in it as the optima in there is at least 4 years old and kind of worn out. So there, a new fuel pump and battery and I'll have all the wrenching I need. :D
If you sell my schiada for me, I will give you 5% of the sale...

[Jordy]

If you sell my schiada for me, I will give you 5% of the sale...
I can't sell mine right now, but I'll add yours to the list. So if I sell it for $100 you're going to give me $5? Sweet. :D

[78Eliminator]

Shaun, you going to jump on those heads or not? You have it in your signature line that you want 990s, but you never jump on them. You will not find any good condition 990 heads for less than $500, I guarantee.....

[Fired Up]

Hey Fiat! WHERE do you find a new set of 12.5:1 TRW pistons for less than $300.? Need to know.......I'm looking for more HP as you well Know. Planning for winter.

[Fiat48]

They run specials on them from time to time. Check a copy of national dragster. Competiton products has done it.
Or since you live so close to Ling beach swap meet...a lot of the piston manufactures take overstock and other pistons to the swap meets and sell them. Most everybody makes a 12.5 to 1 piston for a BBC.
I have a set of new Manley Pro Domes that are 13.5...still in the box. Lighter than a trw but otherwise not much different. But they are .100 over. $300

[steelcomp]

Hey Fiat! WHERE do you find a new set of 12.5:1 TRW pistons for less than $300.? Need to know.......I'm looking for more HP as you well Know. Planning for winter.
You won't get 12:1 with TRW's without a lot of work, and a lot less that 118 cc chambers.

[steelcomp]

Fiat, you soud like a pretty savvy guy when it comes to engines, but I don't get this high compression thing. It's been a few years now since that was the "best" way to build power. With today's chamber designs and cam profiles (and EFI in cars) there's some increadible HP numbers coming out of motors at lower than ever before rpm levels, all on pump gas. 800 hp ouut of a 10:1 500ci. motor is not unreassonable, and that's at a usable rpm. Cam profiles today can way more than make up for lower static compression. Static compression tends to seperate the fuel molecules at a more rapid rate, which is what causes detonation. Dynamic compression, or "cyl pressure" builds at a different rate, not disturbing the fuel and allowing for a much more controlled burn, even on pump gas. That's why chamber shape has so much to do with good or bad burn.
In an all out race motor where you're running 13.5+:1, and using c14 0r c16, and can fully take advantage of that kind of gas, compression is the only way to go, but then you're talking about a motor that isn't going to develope the dynamic cyl pressure in a usable rpm for most jet boats.
396, the idea of keeping your compression at a level where you can use pump gas isn't performance limiting. It's being sensable. Av gas is a poor substitute for race gas, and you won't see the performance gain by running it that you think you will. If you want to run compression, the only way to really take advantage of it is to buy $4.00+ a gallon race gas. That is a pain in the ass, and expensive. If you just take the time to do your OWN research, you can build a pump gas motor that will hand most of these guys their asses. On a single four barrel. :D
steel

[Fiat48]

L2307 Trw piston has a 49cc dome. Trw states:
12.06 to 1 with std bore and 119 cc head
12.21 to 1 with .030 over
12.36 to 1 with .060 over
12.56 to 1 with .100 over
12.69 to 1 with .125 over
Real world.
Take the .030 overbore piston at 4.280
Deck clearance of .025 (basic undecked block should be close)
119 cc head
.040 thick 4.370 (common felpro size) gasket.
Final ratio 12.1
O deck the block with no other changes and you have 12.81 to 1.
Now we could get more by using a round copper gasket of 4.280 bore size to match the bore and/or a smaller cc head....but you get the general idea.

[396_WAYS_TO_SPIT]

Dammit Bob, I keep trying to tell 396 that he needs to be down in the 10:1 range for what he's doing. Running race/av gas gets old really quick on a boat that you want to take to the lake every weekend. The nice thing now about my jet, I just pull up to the pump, top it off with super (which is probably overkill anyway) and roll. No more trips to the aeropuerto with that bad boy. :D
396, I'd rethink that compression deal for what you're looking to do with it.
The problem is I already have money spent on pistons and a cam.If I change my compression then my cam will not work properly. It is designed to be used with a high compression motor. I am going to have to take justin's and bob's side on this one jordy;) Compression=horsepower! Horespower=Rooooster :D I really dont want to go backwars. My bottom end will be built on sunday then all I need to do is find a set of "close" chambered heads.
396

[Jet City]

The problem is I already have money spent on pistons and a cam.If I change my compression then my cam will not work properly. It is designed to be used with a high compression motor. I am going to have to take justin's and bob's side on this one jordy;) Compression=horsepower! Horespower=Rooooster :D I really dont want to go backwars. My bottom end will be built on sunday then all I need to do is find a set of "close" chambered heads.
396
Pistons decks can be machined and you can install the cam on a different CL to deal with static compression differences, I wouldn't feel trapped just yet. I have a boat that runs 12:1 CR now, buying race gas isn't very fun, but it does smell nice. I would also consider oval ports for the Jet, the port velocity is far better for under 6500 rpm range according to my research.

[Fiat48]

As you just mentioned and someone else did earlier...the round ports would work on this deal and may be a better choice. I have no experience in that area and only comment what I have had experience doing.
I didn't mention them for the fact that he already has a square port intake...and he isn't about to change that (I know from many Pm's he sent me).
But I can see velocity benefits with the round ports in these rpm ranges.

[Jordy]

I just have a hard time justifying going to the airport or running race gas for more rooster. Now if you were building something to keep up with the yellow boat, I might understand, but for more rooster??? Sorry bro. :cool: :D :D :D

[steelcomp]

L2307 Trw piston has a 49cc dome. Trw states:
12.06 to 1 with std bore and 119 cc head
12.21 to 1 with .030 over
12.36 to 1 with .060 over
12.56 to 1 with .100 over
12.69 to 1 with .125 over
Real world.
Take the .030 overbore piston at 4.280
Deck clearance of .025 (basic undecked block should be close)
119 cc head
.040 thick 4.370 (common felpro size) gasket.
Final ratio 12.1
O deck the block with no other changes and you have 12.81 to 1.
Now we could get more by using a round copper gasket of 4.280 bore size to match the bore and/or a smaller cc head....but you get the general idea.
Real world:
friend's 467" BBC (+.060 454)
4.310 bore X 4.00 str. (956.49cc)
119.5 cc chamber
Felpro 1037 (9.7cc)
TRW 2307- dome vol (liquid cyl pour) 40.8 cc's (TRW's full of it)
Final CR= 11.82
You can't depend on their info as far as dome vol. You need to measure it yourself, which will also take into consideration the space between the piston and cyl to the top ring. The only thing done to these pistons was to blend and polish the dome, which should be done to any hi dome piston. I don't think this removed 8.2 cc's.
Using your bore and stroke numbers, and the actual dome of 40.8cc's you get a true c/r of 11.06:1 cr.
4.28 X 4.00= 943.2cc
.025 deck= 5.8cc (@ 4.28")
chamber= 119cc
gasket= 9.7cc
dome= <40.8cc>
1036.9 swept vol devide by 93.7 compressed vol= 11.06:1
with zero deck it would be 11.73:1
This is why you have to check your own numbers.
steel

[steelcomp]

The problem is I already have money spent on pistons and a cam.If I change my compression then my cam will not work properly. It is designed to be used with a high compression motor. I am going to have to take justin's and bob's side on this one jordy;) Compression=horsepower! Horespower=Rooooster :D I really dont want to go backwars. My bottom end will be built on sunday then all I need to do is find a set of "close" chambered heads.
396
Run a set of open chamber heads...they breathe much better and will lower your c/r. Cam will work.

[396_WAYS_TO_SPIT]

I just have a hard time justifying going to the airport or running race gas for more rooster. Now if you were building something to keep up with the yellow boat, I might understand, but for more rooster??? Sorry bro. :cool: :D :D :D
Who knows jordy... i might be trying to keep up with ya :D :D Maybe that new droop I am buying from phil tomorrow will help with my speed Oh I mean Roost :D :D Like i said before, falcon field is on the way to the lake and its never closed so I am all good on gas :D
396

[GofastRacer]

I just have a hard time justifying going to the airport or running race gas for more rooster. Now if you were building something to keep up with the yellow boat, I might understand, but for more rooster??? Sorry bro. :cool: :D :D :D
I have no problem going to the airport at all and when I'm at the river, when I go on a beer run I just take the jugs with me and stop at the airport and fill em up!... :D

[Jordy]

Who knows jordy... i might be trying to keep up with ya :D :D Maybe that new droop I am buying from phil tomorrow will help with my speed Oh I mean Roost :D :D Like i said before, falcon field is on the way to the lake and its never closed so I am all good on gas :D
396
Last time we ran the engine was running 7.5:1 with big heavy flat top TRW blower pistons. Things have changed a bit. :D :D :D

[Jordy]

I have no problem going to the airport at all and when I'm at the river, when I go on a beer run I just take the jugs with me and stop at the airport and fill em up!... :D
Do you find that helps your rooster Art? :D :D :D

[GofastRacer]

As you just mentioned and someone else did earlier...the round ports would work on this deal and may be a better choice. I have no experience in that area and only comment what I have had experience doing.
I didn't mention them for the fact that he already has a square port intake...and he isn't about to change that (I know from many Pm's he sent me).
But I can see velocity benefits with the round ports in these rpm ranges.
A good set of 049's with the big valves and a clean up kicks ass over square port heads under 7000 any day!..

[GofastRacer]

Do you find that helps your rooster Art? :D :D :D
No dumb rooster, just go forward!.. :D :D :D :D :D

[GofastRacer]

Shaun, you going to jump on those heads or not? You have it in your signature line that you want 990s, but you never jump on them. You will not find any good condition 990 heads for less than $500, I guarantee.....
I think he's looking for donations!.. :rolleyes:

[Jordy]

No dumb rooster, just go forward!.. :D :D :D :D :D
Ouch. :D :D :D :D

[shaun]

Shaun, you going to jump on those heads or not? You have it in your signature line that you want 990s, but you never jump on them. You will not find any good condition 990 heads for less than $500, I guarantee.....
ya, i actually talked to him a few months back but i was set on finding somebody local to avoid wasted money on shipping but i'm over it... art, i pm'd you (again)... that is if you still have them...

[Some Kind Of Monster]

Now if you were building something to keep up with the yellow boat, I might understand, but for more rooster???
Have you even run your yellow boat yet Jordy?

[GofastRacer]

Ouch. :D :D :D :D
:D :D :D :D :D

[GofastRacer]

ya, i actually talked to him a few months back but i was set on finding somebody local to avoid wasted money on shipping but i'm over it... art, i pm'd you (again)... that is if you still have them...
Back at ya!..

[cstraub]

Cam won't run with low compression? More cam company myths. I've got customers with 260 @ 50 in some 9 to1 SBC. By manipulating dynamic compression with the valve events, you can prop up static and make power.
If the av gas doesn't bother you then run more compression, you will make more power, but around 10 to 1 on pump is max with iron heads.
Ovals or Squares: I work with 3 engine builders in a truck pull class that has to use OEM heads that can be ported. On a tight track with rpms in the 7K to 7500 range, the ovals out perform the squares. On a loose track and they turn them 8500 to 9K the squares walk all over the ovals. At that rpm the ovals don't have enought volume to make up for the limitations of the camshaft.
My $.02
Chris

[Fired Up]

So what you are saying is that instead of dropping my nickels on some fine aluminum heads...I should take my 049's to the local head shop and beef them up, porting, bigger valves,heavier springs. This almost goes in contrast to what Fiat and I had conversations over for some time. I still need more compression though. At 10:1 I'm still only getting 5700-5800 rpm's out of it. I did get 5900 when I put the 9% in the v-drive. Even lost time/speed with the 1050 I put on the motor. If the ovals outperform the squares to 7500 rpm's why arent more people (boat racers) using them?

[steelcomp]

So what you are saying is that instead of dropping my nickels on some fine aluminum heads...I should take my 049's to the local head shop and beef them up, porting, bigger valves,heavier springs. This almost goes in contrast to what Fiat and I had conversations over for some time. I still need more compression though. At 10:1 I'm still only getting 5700-5800 rpm's out of it. I did get 5900 when I put the 9% in the v-drive. Even lost time/speed with the 1050 I put on the motor. If the ovals outperform the squares to 7500 rpm's why arent more people (boat racers) using them?
Are we talking GM ovals or Merlin ovals? The Merlin ovals flow about like a set of GM rectangle port heads. The GM ovals will peter out at about 6000 (ported), and stop flowing at around .600 lift. The Merlin rect port heads are big, (even the 320's...they don't flow that well) and useless below 6000 on anything but a BIG motor. There's some small runner alum heads that are a very good buy, and would work nicely. The Canfield 310's are excellent heads and can be had for about $1400 complete. And the weight savings is significant!!! With a smaller motor, and lower rpm range, you need as much port velocity as you can get. The 990's suck as far as velocity goes and would hurt you in your app. That's a 345 cc port that the Canfield 310cc port outflows mucho. More air through a smaller port= velocity! That's what will benefit you most. If you can afford the alum. definately go for it. Otherwise I'd stick with the Merlin ovals.

[Fired Up]

The 049 stock GM ovals are what I was referring to. My cam has about 630 lift. I found a set of Brodix heads I've got my eyes on. 1.625 valves Tit retainers, 312cc runner size, heavier springs (t0 800 lift), 118cc chamber, $1850.00 new.

[Fired Up]

Sorry,,,typing faster than I can think....1.625 springs, 2.3/1.88 valves.

[Fiat48]

Well, I think I am going to 6 to 1 compression and maybe find some peanut port heads for my motor. They will have velocity for sure. I am stuck with these old square ports tho. Anybody old school enough to need them, let me know.
http://www.***boat.com/image_center/data/520/374DSCF0068.JPG

[396_WAYS_TO_SPIT]

Well, I think I am going to 6 to 1 compression and maybe find some peanut port heads for my motor. They will have velocity for sure. I am stuck with these old square ports tho. Anybody old school enough to need them, let me know.
http://www.***boat.com/image_center/data/520/374DSCF0068.JPG
If I had a motor that would take that kind of head i would. Thats waaaaayyyyy out of my league;)
396

[steelcomp]

Fiat..what's your point?
Nice set of heads. I especially like the scotchbright swirlpolish on your valley pan! :boxed:
These are the 990's on my boat motor.
http://www.***boat.com/forums/attachment.php?attachmentid=6257&stc=1

[Fiat48]

Different motors, different applications and different goals. Probably be some hurt feelings over this:
396:
Jet boat
lake application
wants more power and wants it cheap (like everybody else)
Runs AV gas anyway
Is adamant to keep his closed chamber pistons.
Trying to come up with cylinder heads but is very picky on giving up any compression from what he had originally (whatever that was).
I still say put as much compression in the thing as AV gas will allow. I stated 990's because they are relatively cheap, high demand if you want to sell them and move on. Would this motor run better for his application with the 049 round ports? In all probability, yes. I state that because I have never run them, yet I see the potential and it makes sense that they would. But he won't do that because he has a square port intake. My vocabulary still includes the words "I don't know." If I state something...it is because I have done it. And that is a Hell of a lot different than theory.
But he's back to looking for a set of closed chamber 109 cc heads anyway. Yet it is common knowledge the closed chambers gave up performance when compared to the open chambers.
Fired up:
Flatbottom (a very nice Canyon Marine)
Racing (starting in brackets)
Current primary goal: To go fast enough (100 mph) to be able to race in a class where there are more boats entering. The boat in current state is just way too slow with not enough power to hold a set.
Wants to spend the least money possible (don't we all).
A wise man once told me if I could not afford the right boat to do the job then stay home and quit wasting money trying to race with a boat that was not going to allow me to go fast no matter what I did to the motor. That was Wayne Mettler and wiser words were never spoken. In this case...it's the motor.
I said put compression in the thing (again..as much as you can get) and a set of 990's will do the job. You'll be turning 7000 rpm and eventually more so why dump a bunch of money in a set of oval ports which will not bring the money back when you wind up with aluminum heads down the road anyway? Quit looking for a "magic screw" to turn that is going to make you go faster. It's not going to happen.
Carbureation: Yeah, I tried running two 1050 dominators instead of my 750's and I lost ET. And I had some compression. You don't.
The Cole I have had a "basic" 460 chevy with 990's, a .700 lift roller cam and basic 12.5 to 1 pistons. Ran 100 mph in the high 10's. These basic glorified LS-7's are all you need to do the job. Proven over 20 years.
Now..why compression? Because I found it to be the single cheapest performance factor that gave power throughout the range with no drawbacks except for good fuel. And because I tried to run 100 mph with less compression (in a flat) and found it didn't work for me. Fired Up...I have made all the mistakes for you 20 years ago. You cannot believe what I have tried.
My feeling is you ask questions but yet only look for the answers that you have in your mind to do in the first place. This isn't Pro Stock. It's simply the cheapest methods of improving your performance that are proven. Which didn't come from a Hot Rod magazine. They are things I have done. Not saying it's the only way but one of the cheapest ways. Because if someone has done this shit cheaper than me, I want to meet him.

[texas-19]

396,
Here is some flow #'s i found.
int. 400 500 600 700
049 oval 253 cc 232 250 254 264
merlin oval 260 cc 243 267 280 282
dart oval 265 cc 244 286 311 326
990 sq.port 318cc 233 264 292
exh. 400 500 600 700
049 143 166 173 174
merlin 162 177 186 192
dart 183 211 228 237
990 176 198 204 207
http://www.airflowresearch.com/ (http://http://www.airflowresearch.com/)
click on the article with the spreadsheet
you may have already seen them,but if not then this might help.

[GofastRacer]

396,
Here is some flow #'s i found.
int. 400 500 600 700
049 oval 253 cc 232 250 254 264
merlin oval 260 cc 243 267 280 282
dart oval 265 cc 244 286 311 326
990 sq.port 318cc 233 264 292
exh. 400 500 600 700
049 143 166 173 174
merlin 162 177 186 192
dart 183 211 228 237
990 176 198 204 207
http://www.airflowresearch.com/ (http://http://www.airflowresearch.com/)
click on the article with the spreadsheet
you may have already seen them,but if not then this might help.
Here ya go!.. :)
AirflowResearch! (http://www.airflowresearch.com/)

[396_WAYS_TO_SPIT]

Different motors, different applications and different goals. Probably be some hurt feelings over this:
396:
Jet boat
lake application
wants more power and wants it cheap (like everybody else)
Runs AV gas anyway
Is adamant to keep his closed chamber pistons.
Trying to come up with cylinder heads but is very picky on giving up any compression from what he had originally (whatever that was).
Fiat is a good guy. He has helped me figure out alot of things and answere alot of my umbass questions;).
Here is my deal. origionally I had a 9.5-1 motor with ovals. then i had a chance to get a polished weiand tunnel ram with dual 750dp's holleys(flowed by braswell's in tucson),linkage,stainless hardline and a brand new dooley scoop. So I got this package on a steal. The only problem was my heads didnt match my intake. So I had to change heads. I talked with a local shop thats also been helping me. I told him I wanted a healthy sounding cam that souned mean and worked good with my set up. He told me I had to raise my compression. I told him that i already had bought pistons.He said"you want to go faster ,right". I said well.........."it would be nice". He then replied"well, change the pistons". I said screw it and ordered new ones the next day. thats what got me into this whole deal. I have a real nice piece to go on top of my motor and i am not going to change it at all. Thats why fiat says I am very picky;). I called clay smith cams and talked to him about my cam and a lower compression.He stated that"if you lower the compression then it will sacrifice your performance". My cam is made specifically for high compression. Like fiat said get as much compression as you can;) Compression=Horsepower! So thats why I am being very picky with my compression and heads. By the way I have a set of close chamber heads on the way :D :D thanks to a fellow boat member.Yes i agree, some say it wont work well and others say it will. i guess we will find out. One thing I will say is, next time I will buy open chamber pistons because I now know how hard it is to find close chamber pistons :eek: All the new style heads are all open chamber.
396

[396_WAYS_TO_SPIT]

[QUOTE=Fiat48]Different motors, different applications and different goals. Probably be some hurt feelings over this:
Yet it is common knowledge the closed chambers gave up performance when compared to the open chambers.
QUOTE]
I talked to someone about this. He said they dynoe'd 2 identical 427's one with open chamber and the other with closed chamber heads. He said that the numbers came out identical. this is from someone that has been in superstock boat racing since the late 60's. he has tried everything to be faster in that class! Not saying you are wrong fiat, I'm just stating what someone tol me;)
396

[GofastRacer]

[QUOTE=Fiat48]Different motors, different applications and different goals. Probably be some hurt feelings over this:
Yet it is common knowledge the closed chambers gave up performance when compared to the open chambers.
QUOTE]
I talked to someone about this. He said they dynoe'd 2 identical 427's one with open chamber and the other with closed chamber heads. He said that the numbers came out identical. this is from someone that has been in superstock boat racing since the late 60's. he has tried everything to be faster in that class! Not saying you are wrong fiat, I'm just stating what someone tol me;)
396
How can they be identical???, one is closed chamber and the other is open chamber!..It's been proven since the day open chambers came out that they put out more power!....

[396_WAYS_TO_SPIT]

How can they be identical???, one is closed chamber and the other is open chamber!..It's been proven since the day open chambers came out that they put out more power!....
Identical motors except the heads.Thats what i have been told. I didnt really get into depth about it. all I know is that they know 427's really well. They set up alot of superstock boats. i know this because I have seen alot of them in that shop;)his son did race untill he had a terrible accident. If you want to talk to him give him a call. Phil Bergeron 480-834-1531 I am sure he can give you the run down. the only reason I take alot of his advice is because I never can prove him wrong. He gave me a little tip about my jacuzzi pump that helped me gain more speed. It consiste of removing 1 little bolt and washer :D
396

[Jordy]

I'm going to go out on a limb here and guess that GFR has been to Bergeron's a time or two. ;)

[Fiat48]

[QUOTE=Fiat48]Different motors, different applications and different goals. Probably be some hurt feelings over this:
Yet it is common knowledge the closed chambers gave up performance when compared to the open chambers.
QUOTE]
I talked to someone about this. He said they dynoe'd 2 identical 427's one with open chamber and the other with closed chamber heads. He said that the numbers came out identical. this is from someone that has been in superstock boat racing since the late 60's. he has tried everything to be faster in that class! Not saying you are wrong fiat, I'm just stating what someone tol me;)
396
Any chamber shape which shrouds the valves reduces air flow capability. Which the closed chamber does. Since an engine is just an air pump, reducing flow reduces HP output.
Comparison of STOCK UNPORTED Chevrolet heads 2.19 intake and 1.88 exhaust valve sizes.
Air flow: Intake
Valve lift Closed chamber Open chamber
.150 127 200
.200 208 280
.250 307 360
.300 392 420
.350 480 517
.400 560 613
.450 610 695
.500 655 795
.550 700 875
.600 742 885
Now....which head is going to make more power?
Chevrolet stated in 1969:
Air flow through the open-chamber head when combined with the new pistons improved 30% over the first design (closed chamber) L-88 aluminum or cast iron heads.

[396_WAYS_TO_SPIT]

Damn, you went to the closet on me an dug up some good info;) Well that makes perfect sense to me;)
396
Any chamber shape which shrouds the valves reduces air flow capability. Which the closed chamber does. Since an engine is just an air pump, reducing flow reduces HP output.
Comparison of STOCK UNPORTED Chevrolet heads 2.19 intake and 1.88 exhaust valve sizes.
Air flow: Intake
Valve lift Closed chamber Open chamber
.150 127 200
.200 208 280
.250 307 360
.300 392 420
.350 480 517
.400 560 613
.450 610 695
.500 655 795
.550 700 875
.600 742 885
Now....which head is going to make more power?
Chevrolet stated in 1969:
Air flow through the open-chamber head when combined with the new pistons improved 30% over the first design (closed chamber) L-88 aluminum or cast iron heads.

[GofastRacer]

Identical motors except the heads.Thats what i have been told. I didnt really get into depth about it. all I know is that they know 427's really well. They set up alot of superstock boats. i know this because I have seen alot of them in that shop;)his son did race untill he had a terrible accident. If you want to talk to him give him a call. Phil Bergeron 480-834-1531 I am sure he can give you the run down. the only reason I take alot of his advice is because I never can prove him wrong. He gave me a little tip about my jacuzzi pump that helped me gain more speed. It consiste of removing 1 little bolt and washer :D
396
I been around SS's for over 25 years and I've known Bergeron for almost the same time!..Open chamber heads make more power than closed chamber, check the flow numbers!..

[GofastRacer]

I'm going to go out on a limb here and guess that GFR has been to Bergeron's a time or two. ;)
Nope, I don't go there!.. :rolleyes:

[cstraub]

Even with identical heads, engines will have a slight difference in power so their is no way that these 2 produced the same power rpm to rpm. Rolling of the chamber out will make more power due to the fact that the open chamber inhances the flow into it and during ignition promotes a much better flame travel to ignite the fuel/air mixture. My 2cts.

[Fired Up]

Fiat,
Sorry I could not respond sooner, but I've been at work the last three days. We can't access the website from the employers computer. I've kept the info you've fed me over the last year as a source of referrence. My intent this winter IS to build the compression (12:1), better cam (700+lift), and stronger rods (eagle 7/16-h beams). I've "played" with different carb set ups, timing, gears,props lately...simply because with only a few races left I thought it better to get seat time and learn, than miss races because the motor wasn't finished in such a short time.
Now the oval heads, ....I only made the point about the heads earlier because of the post that cstraub69 said caught my eye in contrast to what the general consensus was. That someone was running oval ports to over 7000 rpm's and making good power with them over square ports. Hmmmm..made me think.
In the heydey of muscle cars (1960's-1970's)when you had BBC's running (9:1,10:1) stock street compression in your corvettes, camaros, chevelles didn't they run square ports? And they didn't turn anything near 8000 rpm's on the street cars. Whats to keep me from just dropping a set of square ports (alum or iron) and get more HP?
Fired Up

[Taylorman]

Well, I think I am going to 6 to 1 compression and maybe find some peanut port heads for my motor. They will have velocity for sure. I am stuck with these old square ports tho. Anybody old school enough to need them, let me know.
http://www.***boat.com/image_center/data/520/374DSCF0068.JPG
Are those Jesel rocker arms?

[Fiat48]

Taylorman:
Yes, that is the Jessel setup. Actually the only reason that they are on there is that is the way I bought the heads. The reason the guy sold the heads was because he had a lot of valve train failures because the rocker geometry was never right. I straightened that out and did run the Jesel setup. If they had not come with the heads, I would have just put a good set of studs, guideplates and a set of Crane or other roller rockers on. Never could justify the expense of shaft rockers. But other guys do like them.
Fired up:
Just don't want you wasting money and traveling expensive routes when all it takes is the basics to do the job you want to do. When you go 100 mph...you'll want to go 102 mph. That's the way it all starts.
Chevrolet's answer for more Hp in the big block was the square port head AND more compression (larger camshaft also). I can't bring any experience to the table on just adding the square port head without adding compression. We've always done the compression and the heads at the same time. But one experience I had with a set of Arias pistons (long ago) that were not the compression they were supposed to be (actually about 10.5 compression), the boat would not break the 100 mph mark until we discovered that and changed pistons. Getting the motor to actual 12.5 made a world of difference everywhere. Left harder and ran harder..the whole way down the course. So I think you need the compression and the heads.
So the next step was even more compression until we couldn't get anymore. Around 15.3. I was even decking blocks and sticking the piston out of the deck, then milling off the pistons to clear the deck of the head. Then fitting the dome as tight to the head as possible and letting the gasket be my deck clearance. I'll even confess this. Because I had little money I even had material added (as in welding) to the domes of the pistons. :220v: And you wouldn't believe who welded those pistons for me. Very famous cylinder head guy thought it was a grand idea. Then the camshafts got bigger (compression covers up big cams), then retarded camshaft phasing and on and on. But that is way beyond your needs.
There's many ways to do it. Simple low budget way for you to do it is to buy a set of 990 (or aluminum similar) heads, a piston with near a 50 cc dome and your near .700 lift camshaft and you should be where you want to be.
Basically an LS-7 with a roller cam is all you need.
You're near the land of Swap meets (Pomona and Long beach) and with winter (less than 80 degrees is your winter :D ) approaching there should be bargains for sure.

[steelcomp]

I'm thinking of selling the 990's off my boat. I need to lighten the boat up, and a set of aluminum heads is the first big step in getting that done, not to mention picking up a little more power.
http://www.***boat.com/forums/attachment.php?attachmentid=6257&stc
http://www.***boat.com/forums/attachment.php?attachmentid=6524&stc=1
http://www.***boat.com/forums/attachment.php?attachmentid=6528&stc=1
They have been moderately ported, but not radically. No serious change in port shape, just straightened out the walls, opened the intakes to the blu print dimensions, raised the tops of the exhausts as much as I could, blended the bowls, worked the guide bosses a little, and spent most of the time in the chambers. They are at 117cc +/- .1 cc, and the tops of the pistons show an excellent burn...not the BBC's strong point. 2 1/4" intake w/4 angle valve job, Manley ProFlo's, Isky 8005A springs (for flat tappet) Ti retainers, Comp Keepers. ARP studs, and the guide plates were indexed to put the rocker tip over the valve. Heads have been de burred, casting flash removed, and polished for oil return. These heads had never been valve jobbed before, so the ex seats are nice and high. I did spend significant time widening the short turn and slightly laying back the intakes. There's not much you can do with the ex. short turns, except to widen them as well. Most guys would consider this a full port job. It's about the nicest set of 990's you'll find, without being "radical". I never did get a chance to flow them, but I can say with confidence that they're as good as any other ported set of 990's. The only thing I regret not doing is backcutting the intakes.
Anyone interested let me know.

[GofastRacer]

How much??, one of my car guy buddies asked me about some 990's!..

[steelcomp]

$1200.00...I know, not cheap, but worth it. Very low time...less than 5 hrs.

[steelcomp]

Fiat wrote:
Never could justify the expense of shaft rockers. But other guys do like them
I like 'em.
I used to say the same thing, but if you think about it, you're only spending a few hun more, and get a lot of benefits.
NO stud girdle to **** with
No stud flexing (even with girdle)
WAY more durable and dependable
easier and more consistant valve adjustment and lash
maintains geometry better= more hp (10-15 more w/ BIG springs)
just my .02

[GofastRacer]

$1200.00...I know, not cheap, but worth it. Very low time...less than 5 hrs.
That's not a bad price, I'll let him know!..